Low oil pressure control system for air compressors

ABSTRACT

A low oil pressure protection system for an air compressor control wherein a logic device is utilized to render said compressor inoperable when low oil pressure occurs, and timing means actuated during normal restarting cycles of the compressor after normal governor controlled stopping, to override protection control by said logic device.

United States Patent Coiner 14 1 Apr. 4, 1.972

[54] LOW OIL PRESSURE CONTROL 1,936,821 11/1933 SYSTEM FOR AIR COMPRESSORS 3,478,731 11/1969 2,793,803 5 1957 [72] Inventor: Ronald W. Colner, Irwin, Pa. 3,499,599 311970 [73] Assignee: Westinghouse Air Brake Company, Wil- 2,130,608 9/1938 merding, Pa. 1,400,133 12/1921 [22] Med: May 1970 Primary Examiner-William 1.. Freeh [21] Appl. No.: 40,145 Attorney-Ralph W. McIntire,Jr.

52 us. 01 ..417/12, 417/13 1571 ABSTRACT [51] Int. Cl ..F04b 49/00 A low on pressure protection system for an compressor [58] Fleld of Search ..417/13, 12, 26, 28, 44 control wherein a logic device is utilized to render Said pressor inoperable when low oil pressure occurs, and timing [56] References Cited means actuated during normal restarting cycles of the com- UNITED STATES PATENTS pressor after normal governor controlled stopping, to override 1 protection control by said logic device. 3,105,629 10/1963 Van Vooren ..417/l3 3,250,285 5/1966 Vockroth, Jr ..137/81.5 2 Claims, 1 Drawing Figure FROM COMPRESSOR OIL PUMP OUTLET LINE 4 Ex COMPRESSOR F '2 GOVERNOR 16- -l0u I 8 1- NOR DCV I3 14 I8 I BATTERY TO INDICATOR PATENTEDAPR 41912 5 3,653,782

FROM COMPRESSOR on. PUMP OUTLET LINE 4 EX COMPRESSOR 2 GOVERNOR 3L V A 5 6 g 8 l IO NOR DCV -6 EX I3 |4 BATTETM To INDICATOR INVENTOR. RONALD W COINER ATTORNEY 1 7 LOW OIL PRESSURE CONTROL SYSTEM FOR AIR COMPRESSORS BACKGROUND OF INVENTION In air compressor controls it is desirable to have a protection system wherein compressor operation is stopped when the oil pressure scheme fails, and means for overriding said protection system during initial starting of said controls in a normal governor-controlled running and stopping cycle.

SUMMARY OF INVENTION According to the present invention there is provided an air compresor control including a low oil pressure sensing scheme utilizing a logic device to render the air compressor inoperative when the oil pressure therein is insufficient, and timing means operative with said logic means to prevent shutdown of said compressor control for a predetermined time interval during a governor controlled starting cycle of said compressor, until the oil pressure has sufficient time to build-up.

In the accompanying drawing there is shown the logic circuitry including in block form a logic device, check valve device and timing means for providing a compressor control means.

The compressor protection system comprises a pneumatic NOR logic device 1, a timing means including a reservoir 2 and a choke 3, governor means 4 connected to the compressor, oil pressure indicating means 5 connected to the compressor, double check valve 6, signal means 7, main reservoir supply means 8 for supplying any operating means (not shown) as controlled by compressor 9 shown in a box form.

As shown in the drawing under normal starting operating conditions when the pressure in the main reservoir supply means 8 drops below a predetermined low pressure through normal usage, the governor means 4 operates in a well-known manner to vent a control pipe 10 which in turn vents a regulating pipe 11 via the right side of the double check valve 6 to cause operation of the electric switch portion 12 to start the compressor in a usual well-known manner.

The pneumatic NOR logic device 1 is operable to permit flow of supply or main reservoir pressure from main reservoir 8 to supply port 13 and through the logic device 1 in its "open condition to output port 14 when there is no oil pressure at input 15 from the oil line 16 to the compressor and no pressure at input 17 from the supply line 10 and 10a to the compressor governor 4. Pressure at either or both inputs 15 and 17 effects a closed condition to interrupt output pressure at port 14 to a line 18 leading to the left-side of the double check valve 6 and also to a signal means 7.

The chock 3 and timing reservoir 2 are connected between the supply lines 10 and 10a in a manner to slow down venting of NOR input 17 and supply line 10a to the supply line 10 which in turn is venting at the governor 4 during the starting operation just described. It can thus be seen that during the described starting operation, the pressure at input 17 is maintained a short time interval while the timing reservoir 2 vents via the choke 3 and supply line 10 to atmosphere, thereby causing the logic device 1 to remain closed to prevent supply of main reservoir pressure to the line 18 at output port 14. At the end of the time interval for venting the input 17, the oil pressure at input 15 is normally built up to maintain the logic device 1 in its described closed condition with no output at port 14. In the event that the oil pressure has not builtup at input 15 during this time interval, the logic device 1 will operate responsively to the lack of pressure at inputs 15 and 17 to condition to an open condition to supply main reservoir pressure to the output port 14 and line 18. Supply of fluid under pressure to line 18 effects first an operation of signal means 7 to energize a light, buzzer, etc. (not shown) to indicate lack of oil pressure, and secondly to supply fluid under moiphere, thus the just described su ply of main reservoir flul under pressure to the left-hand 81 e will cause the double check valve to operate in a usual manner to permit the supply of main reservoir pressure to be connected to regulating pipe 11 and the electric portion 12 of the compressor to thereby stop the compressor and prevent damage thereto due to low oil pressure.

This just described shut-down condition of the compressor is maintained until the pressure in main reservoir 8 and consequently in regulating pipe 11 is depleted to a degree insufficient to effect operation of the electric portion to maintain the compressor stopped. At this time, the governor 4 will again attempt to start the compressor and if the faulty oil pressure condition has been corrected, oil pressure will build up in line 16 to the input 17 to close" the NOR logic device 1 and permit normal operation of the compressor under the control of governor 4. If oil pressure still does not materialize, the compressor will only operate a relatively brief period until the main reservoir pressure develops sufiiciently to effect operation of the electric portion to again terminate compressor operation. In this manner, the compressor will remain effective to maintain the main reservoir charged to a minimum pressure for use in the event the vehicle is operating as a single car unit such that there is no air pressure available from the compressors of other cars.

Having now described the invention, what I claim as new and desire to secure by Letters Patent, is:

l. A compressor control system for regulating operation of a compressor apparatus in accordance with the lubricating oil pressure at said compressor, said system comprising:

a. an oil pipe means containing oil under pressure of lubricating oil at said compressor,

b. control pipe means subject to fluid under pressure therein,

c. regulating pipe means including an electric switch for regulating starting and stopping of the compressor respectively in accordance with the venting or the supply of fluid under pressure therein,

d. reservoir means chargeable with fluid under pressure from the output of the compressor,

e. governor means operably responsive to a predetermined range of fluid under pressure in said reservoir means for effecting charging or venting of said control pipe and said regulating pipe to effect respectively, stopping and starting of said compressor and,

f. a pneumatic logic valve having:

i. a first input subject to oil pressure in said oil pipe,

ii. a second input subject to fluid pressure in said control pipe,

iii. a supply port subject to fluid pressure of said reservoir,

and

iv. a delivery port communicated with said supply port only in the absence of fluid pressure at said first and second inputs to provide an alternate supply of fluid pressure to said regulating pipe means whereby said electric switch is actuated to stop operation of said compressor only so long as fluid pressure of said reservoir is sufficient to maintain said electric switch in the actuated condition, and

g. timing means associated with said second input for delaying venting of fluid under pressure at said second input during a compressor starting operation while the pressure to said first input is normally increasing.

2. The combination as claimed in claim 1 further characterized by including an indicating means for indicating delivery or non-delivery of fluid under pressure from said delivery port. 

1. A compressor control system for regulating operation of a compressor apparatus in accordance with the lubricating oil pressure at said compressor, said system comprising: a. an oil pipe means containing oil under pressure of lubricating oil at said compressor, b. control pipe means subject to fluid under pressure therein, c. regulating pipe means including an electric switch for regulating starting and stopping of the compressor respectively in accordance with the venting or the supply of fluid under pressure therein, d. reservoir means chargeable with fluid under pressure from the output of the compressor, e. governor means operably responsive to a predetermined range of fluid under pressure in said reservoir means for effecting charging or venting of said control pipe and said regulating pipe to effect respectively, stopping and starting of said compressor and, f. a pneumatic logic valve having: i. a first input subject to oil pressure in said oil pipe, ii. a second input subject to fluid pressure in said control pipe, iii. a supply port subject to fluid pressure of said reservoir, and iv. a delivery port communicated with said supply port only in the absence of fluid pressure at said first and second inputs to provide an alternate supply of fluid pressure to said regulating pipe means whereby said electric switch is Actuated to stop operation of said compressor only so long as fluid pressure of said reservoir is sufficient to maintain said electric switch in the actuated condition, and g. timing means associated with said second input for delaying venting of fluid under pressure at said second input during a compressor starting operation while the pressure to said first input is normally increasing.
 2. The combination as claimed in claim 1 further characterized by including an indicating means for indicating delivery or non-delivery of fluid under pressure from said delivery port. 